• Type THHN Building Wire is intended for general purpose applications and may be installed in conduit, duct, or other recognized raceways in wet (60°C oil/90°C water) or dry (105°C) locations. • For both new work and rewiring applications, the smaller diameter of the wire permits additional circuits or larger conductors to be installed in the conduit without exceeding maximum fill limitations. • The insulation is a high quality, heat and moisture resistant polyvinyl chloride compound over which a heat and light stabilized nylon jacket is tightly applied.